Helmet characterized by negative lift

Abstract

There is disclosed a helmet useful for crew members of an aircraft from which they may be ejected at high speeds. The helmet comprises a shell which fits over the head in a conventional manner and is provided with a strap which passes beneath the chin to retain the helmet on the head. A visor housing attached to, and spaced from, the shell is positioned to cover the forward crown part of the head and has portions which extend downwardly along the sides of the face of the wearer, which merge into the planes of flat areas at the ears. By this structure the usual bulbous shape at the ears commonly found in helmets is avoided and the side-to-side dimension is reduced. There are formed at the upper part of the visor housing a number of discontinuous louvers forming ridges through forward facing walls of which there are apertures. During an ejection, air scooped into the region between the visor housing and the shell exits through these louver openings. A openable closure at the rear of the visor housing closes this space between the visor housing and the shell at the rear so that the air scooped within the visor housing will not emerge from the rear. The effect of the ridges and the apertures is to disrupt the smooth air flow over the top of the helmet which would otherwise occur and which would cause undesirable lift.

We claim: 
     
       1. In a helmet adapted for use in aircraft and during ejection therefrom, said helmet being of the type having a shell covers the wearer's head, a visor housing spaced from and covering, an upper part of the shell, a visor retractable within the space between the shell and the visor housing and strap means for securing the helmet to the head of a wearer: ridge means extending laterally and protruding upwardly at the top of the visor housing;   whereby when a wearer is ejected from an aircraft moving through the air there is created a disruption of the flow of air over the top of the helmet, resulting in reduction of the lift which would otherwise occur.   
     
     
       2. Equipment according to claim 1 in which said ridge means comprises a plurality of laterally extending ridges. 
     
     
       3. Equipment according to claim 2 in which there are discontinuities of the ridges. 
     
     
       4. Equipment according to claim 3 in which the ridges contain apertures positioned in forward facing walls of said ridges and a closure closes the space between the shell and the visor housing at the rear of the visor housing and a slot extends forwardly through the visor housing from an upper part of said housing toward the front of said housing; and handle means attached to the visor and protruding through the slot to a position above the visor housing where it can be manually moved along the slot to extend and retract the visor, said handle means comprising a lock for locking the handle means to the visor housing to prevent movement of the visor, and manually operable means for releasing the lock so that the visor can be moved.   
     
     
       5. Equipment according to claim 4 in which said closure is openable to provide access to the visor within the visor housing. 
     
     
       6. Equipment according to claim 5 in which said lock comprises a first member which engages the outer wall of the visor housing and a second member movable relative to said first member, which engages the inner wall of the visor housing, spring means urging said first and second members to move toward each other to grip the visor housing wall between them to produce the locking effect, and manually operable actuator means outside the visor housing to push said first and second members apart for releasing the lock and permitting sliding of the visor. 
     
     
       7. Equipment according to claim 6 in which the sides of the shell located outside the ears of the wearer are in the form of flat planar areas parallel to each other and the visor housing and is provided with depending portions at each side of the face and in front of the respective flat planar areas, each depending portion containing a flat area co-planar with the respective planar area of the shell. 
     
     
       8. Equipment according to claim 1 in which said ridge means contains apertures through which air flows outward from the visor housing during an ejection. 
     
     
       9. Equipment according to claim 8 in which said ridge means has a forwardly facing wall means and said apertures are positioned through said forward facing wall means. 
     
     
       10. Equipment according to claim 8 in which said ridge means has a rearwardly facing wall means and said apertures are positioned through said rearwardly facing wall means. 
     
     
       11. Equipment according to claim 8 in which said helmet is provided with a closure which closes the space between the shell and the visor housing at the rear of the visor housing, thereby preventing exiting of air through said space at the rear of the visor housing. 
     
     
       12. Equipment according to claim 11 in which said closure is openable to provide access to the visor within the visor housing. 
     
     
       13. Equipment according to claim 12 in which said closure is rendered openable by slot means and pin means at the lower sides of the helmet, said closure being openable and closeable by pivoting of said pin means through said slot means, said slot means being elongated and slanted downwardly and rearwardly. 
     
     
       14. Equipment according to claim 13 in which a lip is formed on the outer edge of said closure and an inwardly protruding lip is formed at the rear edge of said visor housing such that the lip of the closure engages in front of the lip of the visor housing to maintain the closure in a closed position, said lips being disengageable from each other to permit opening of the closure by downward and rearward pressure on the closure at the pin means and slot means. 
     
     
       15. Equipment according to claim 1 in which the sides of the shell located outside the ears of the wearer are in the form of flat planar areas parallel to each other and the visor housing is provided with depending portions at each side of the face, and in front of the respective flat planar areas, each depending portion containing a flat area co-planar with the respective planar area of the shell.